锡兰绿茶中黄酮类成分对缺氧人脑上皮细胞的治疗作用

为研究从锡兰绿茶（Dilmah）提取纯化的黄酮类有效成分对缺氧人脑上皮细胞的治疗作用，体外培养人脑上皮细胞（HBEC），给与锡兰绿茶黄酮提取物治疗后造缺氧模型，检测锡兰绿茶中的黄酮类化合物的抗氧化活性及脑细胞的生存情况，探究其对缺氧脑细胞氧化应激的影响。生化检测显示锡兰绿茶提取物的自由基的清除抑制率（ABTS）为68％±2．8％，次氯酸漂白邻苯三酚红抑制率为79％±4．5％。缺氧后，空白对照组细胞生存率为29％±2．3％，而锡兰绿茶黄酮提取物治疗组为41％±4．7％，氯沙坦治疗组为39％±3．1％。同时，黄铜提取物与氯沙坦治疗组LDH释放分别减少75％±3．7％和79％±3．5％。锡兰绿茶的黄酮提取物治疗使细胞抗氧化酶活力显著增强，SOD：（1．5±0．6）μmol／min／mg蛋白，CAT：（0．61±0．06）μmol／min／mg蛋白，GPx：（2．6±0．41）μmol／min／mg蛋白，GST：（6．0±2．4）μmol／min／mg蛋白，显著高于缺氧对照组，其酶活力分别为：（0．5±0．52，51±0．04，1．2±0．35，3．1±1．6）μmol／min／mg蛋白。研究结果表明，锡兰绿茶有很大的临床应用价值。饮用锡兰绿茶可能成为预防中风的有效新方法，并能减少现代疾病对生命的威胁，提高人类生活质量。

Therapeutic effects of flavonoids from Ceylon green tea on hypoxic human brain epithelial cells

We have extracted and purified flavonoids as active ingredients from Ceylon green tea （Dilmah）. In this project, an in vitro hypoxic model using human brain epithelial cells （HBEC） was studied with treatment of the tea extract before inducing hypoxia. We have tested the hypothesis that flavonoids extracted from Ceylon green tea act as potential therapeutic ingredient （s） to reduce oxidative stress in hypoxic cells through its antioxidant properties and its ability to reduce cerebral cellular death. The biochemical antioxidant tests show that the Ceylon green tea has 68% ± 2.8% inhibition property of scavenging of ABTS. The inhibition of pyrogallol red bleaching by HOCI from Ceylon tea was 79% ± 4.5%. After exposing to hypoxia, the cell viability was 29% ± 2.3% in the hypoxia control group but 41% ± 4.7% for flavonoids extract treated group. In LDH assay, flavonoids extract treated group had 75% ± 3.7% reducing of LDH release. The flavonoids extract treated groups significantly increased in antioxidant enzyme activity assays： the activity level of SOD （1.5 ± 0.6） μmol/min/mg protein], CAT （0.61 ± 0.06） μmol/min/mg protein], GPx （2.6 ± 0.41） μmol/min/mg protein] and GST （6.0 ± 2.4） μmol/min/mg protein] are significantly increased as compared with hypoxic control （0.5 ± 0.52, 0.51 ± 0.04, 1.2 ± 0.35 and 3.1 ± 1.6） μmol/min/mg protein, respectively]. The study demonstrated a great clinical potential and opened a new avenue to prevent stroke by drinking Ceylon tea.